Black's 5th move seems to be a serious mistake, and I get a crushing iniative after this!
Try to figure out white's compensation/next sequence of moves.
The complete game with light notes:
Game In 3 Minutes - I was white.
[Event "ICS Unrated blitz match"]
[Site "freechess.org"]
[Date "2013.01.11"]
[White "paulbuchman"]
[Black "GuestJBRL"]
[WhiteElo "2103"]
[BlackElo "0"]
[TimeControl "180"]
1.d4 Nf6 2.Nf3 {I always remember Seirawan's note here. This dodges the 3 B's (Benoni,Budapest,& Benko).} c5 {He wants a Benoni type position anyway. White has quite a few tries here. 3.e3 is a Colle move. 3.c3 can be a London or Torre waiting move. 3.dxc5 or 3.g3 are for people who like to experiment.} 3.d5 {Considered Best} b5 {A Benko Gambit without the gambit ... Actually, black just takes some space on the queenside. Black's problem is that he isn't developing any pieces.} 4.Bg5 {Played by Kasparov and good enough for me} Qb6 {I was expecting Ne4. Here I decided to sac a pawn to split the black army right down the middle.} 5.d6 {Playable, but probably not best ... Most definitely blitz worthy. The computer suggests 5. ... h6 among others.} Qxd6 {A Mistake ... White's gamble totally pays off.} 6.Qxd6 {Starting a forced sequence} exd6 7.Bxf6 gxf6 8.Nc3 {Black tends to the b5 pawn, and white hops in at d5.} b4 {same response to a6 ...} 9.Nd5 {Honestly, this is all I say when I decided to sac the pawn. I didn't really need concrete analysis. I knew black's army would be all separated and undeveloped. The black kingside pawns are wrecked. Black has no development, and there are problems at f6 and c7. In addition, there are doubled backward pawns on an open d file. What more could white want?} Kd8 {If 10.Nxf6 Bg7 skewers b2!} 10.O-O-O {defending b2 and renewing the Nxf6 threat} Be7 {Holding the f6 pawn and preparing Bb7 to eliminate the attacker of f6} 11.Nh4 {If not for this move, white's attack wouldn't be as strong. I hadn't planned it in the beginning, but good moves just seem to flow from sound positional advantages.} Bb7 12.Nxe7 {Just in time ... White swaps a good knight for a weak bishop but gains a pawn in the process. The remaining black d pawn and f pawns are still very weak.} Kxe7 13.Nf5+ Ke6 {His king is feeling brave!} 14.Nxd6 {with tempo} Bc6 15.e4 {preparing my next move} a5 16.Bc4+ { I was hoping for Ke5 when all I need is a white pawn on f4!} Ke7 17.Rhe1 {Rather than grab f7, I decided to get the last piece into play. The threat is stronger than the execution!} Rf8 {Here I overdo it a bit. This is my first misstep of the game.} 18.e5 {I saw Bxg2 19.exf6+ Kxf6, but I didn't realize how secure his king is on f6! Black would still be slightly worse, but white's attack is much harder there.} fxe5 {Luckily black errs ... Not really surprising since it's a blitz game and he's been defending the whole time.} 19.Rxe5+ Kf6 20.Rf5+ Kg7 {Rather than go pawn hunting on f7, I decided to keep the attack going. } 21.Rd3 Na6 22.Rg3+ {Black is in serious trouble.} Kh8 {Here I made another innacuracy. The move I played is good enough to win, but I had better.} 23.Nxf7+ {Wins the rook and forces resignation but ... 23.Rfg5 is a mating net. The main idea is Rg8 Rxg8 Nxf7, deflecting the rook and capturing on f7 with mate!}
Position after the better move 23.Rfg5 ... White mates by force.
Sample mates:
[Result "1-0"]
[FEN "r4r1k/3p1p1p/n1bN4/p1p3R1/1pB5/6R1/PPP2PPP/2K5 b - - 8 1"]
[SetUp "1"]
{--------------
r . . . . r . k
. . . p . p . p
n . b N . . . .
p . p . . . R .
. p B . . . . .
. . . . . . R .
P P P . . P P P
. . K . . . . .
black to play
--------------}
1... a4 2. Rg8+ Rxg8 3. Nxf7#
{White mates} 1-0
[Result "1-0"]
[FEN "r4r1k/3p1p1p/n1bN4/p1p3R1/1pB5/6R1/PPP2PPP/2K5 b - - 8 1"]
[SetUp "1"]
{--------------
r . . . . r . k
. . . p . p . p
n . b N . . . .
p . p . . . R .
. p B . . . . .
. . . . . . R .
P P P . . P P P
. . K . . . . .
black to play
--------------}
1... h6 2. Rh5 Kh7 3. Nf5 d5 4. Rxh6#
{White mates} 1-0
[Result "1-0"]
[FEN "r4r1k/3p1p1p/n1bN4/p1p3R1/1pB5/6R1/PPP2PPP/2K5 b - - 8 1"]
[SetUp "1"]
{--------------
r . . . . r . k
. . . p . p . p
n . b N . . . .
p . p . . . R .
. p B . . . . .
. . . . . . R .
P P P . . P P P
. . K . . . . .
black to play
--------------}
1... h6 2. Rh5 Be4 3. Nxe4 Kh7 4. Nf6+ Kh8 5. Rxh6#
{White mates} 1-0